How a protein stops cells from attacking their own DNA

(Image: Pixabay CC0) - Scientists at EPFL have demonstrated the mechanism that allows cells to fight off viral DNA without triggering an immune response against their own genetic material. Viruses multiply by injecting their DNA into a host cell. Once it enters the intracellular fluid, this foreign material triggers a defense mechanism known as the cGAS-STING pathway. The protein cyclic GMP-AMP Synthase (cGAS), which is also found inside the fluid, binds to the invading DNA to create a new molecule. This, in turn, binds to another protein called Stimulator of Interferon Genes (STING), which induces an inflammatory immune response. Sometimes, the material contained inside the fluid - and in contact with the cGAS protein - comes not from a virus but from the cell itself, for instance after the nucleus has accidentally ruptured. When this happens, the cGAS-STING pathway isn't activated.